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BI Halperin

Publications and source records attributed to BI Halperin.

At least 19 recordsLinked to original sources
PubMed2000

Spin configurations of a carbon nanotube in a nonuniform external potential

We study, theoretically, the ground state spin of a carbon nanotube in the presence of an external potential. We find that when the external potential is applied to a part of the nanotube, its variation changes the single electron spectrum significantly. This, in combination with Coulomb repulsion and the symmetry properties of a finite length armchair nanotube, induces spin flips in the ground state when the external potential is varied. We discuss the possible application of our theory to recent measurements of Coulomb-blocked peaks and their dependence on a weak magnetic field in armchair carbon nanotubes.

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PubMed2000

Fluctuating spin g-tensor in small metal grains

In the presence of spin-orbit scattering, the splitting of an energy level varepsilon(&mgr;) in a generic small metal grain due to the Zeeman coupling to a magnetic field B--> depends on the direction of B-->, as a result of mesoscopic fluctuations. The anisotropy is described by the eigenvalues g(2)(j) ( j = 1,2,3) of a tensor G, corresponding to the (squares of) g-factors along three principal axes. We consider the statistical distribution of G and find that the anisotropy is enhanced by eigenvalue repulsion between the g(j).

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PubMed2000

Conductivity tensor of striped quantum hall phases

We study the transport properties of pinned striped quantum Hall phases. We show that, under quite general assumptions, the macroscopic conductivity tensor satisfies a semicircle law. In particular, this result is valid for both smectic and nematic stripe phases, independent of the presence of topological and orientational defects such as dislocations and grain boundaries. As a special case, our results explain the experimental validity of a product rule for the dissipative part of the resistivity tensor, which was previously derived by MacDonald and Fisher (cond-mat/9907278) for a perfect stripe structure.

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